Are you tired of dealing with a smelly bathroom sink? The culprit may be a missing or faulty P-trap.
This essential plumbing component prevents sewer gases from entering your home and keeps your sink drain flowing smoothly. Installing a P-trap under your vanity sink may seem daunting, but with the right tools and instructions, it can be a DIY project that saves you money and hassle in the long run.
In this article, we’ll guide you through the steps to install a P-trap under your vanity sink, so you can breathe easy and enjoy a fresh-smelling bathroom.
How To Install P-trap Under Vanity Sink
Step 1: Gather Your Materials
Before you begin, make sure you have all the necessary materials on hand. You’ll need a trap adapter, a wall bend (long elbow joint), a P-trap adapter (if not included in your kit), and a pop-up drain assembly for your sink. You may also need a hole saw, a laser level, and a speed square.
Step 2: Mark and Cut the Hole
If you have a brand new vanity, the first step is to make a hole in the vanity top. Use a laser level to mark the hole placement and ensure it is square with the vanity. Ideally, you want the center of the faucet aligned with the drain hole. To figure out the distance, refer to your faucet’s spec sheet and mark the location for the drain hole measuring from the wall. Use a hole saw slightly larger than the diameter of your sink’s drain hole and slowly drill through the vanity top.
Step 3: Install the Trap Adapter
Attach the trap adapter to your sink’s drain pipe before proceeding. The trap adapter will allow you to use screw-on fittings in your setup. Attach the wall bend (long elbow joint) to your trap adapter. For complicated projects, you may want to contact customer service for assistance.
Step 4: Install the P-Trap
If your kit does not come with a P-trap adapter, purchase one separately. There are two solutions to modify an S-trap into a P-trap: use an Air Admittance Valve at the top horizontal section or extend the top horizontal section to at least 2X the P-trap diameter. The solution shown in the video has at least 2.5″ of horizontal section, but you may want to increase that to prevent any problems.
Parts used for the connection include a P-trap kit that includes the marvel to PVC adapter, a 90 Degree 1-1/2in PVC Connector, and a short length of 1 1/2in PVC pipe. You’ll also need PVC cement glue and a hacksaw to cut the P-trap kit and PVC pipes to length.
Step 5: Connect to Wall Drain
The new bathroom vanity may have a fixed shelf that is directly below the drainpipe in the wall. Therefore, the P-trap cannot be installed in its regular location (hanging below the wall drain). Use a 90 Degree 1-1/2in PVC Connector Spigot x Socket for the lower connection to the wall drain if you have copper drain pipe. You do not need this if you have a PVC wall drain pipe.
Step 6: Final Install
Once all parts are connected, use PVC cement glue to secure them in place. Make sure everything is tight and secure before turning on water flow.
Remove Old P-Trap And Clean Pipes
Before you can install the new P-trap, you’ll need to remove the old one and clean out any debris from the pipes. This is an important step to ensure proper drainage and prevent future clogs.
Step 1: Turn Off Water Supply
Before you begin, turn off the water supply to the sink. This will prevent any water from flowing while you work on removing the P-trap.
Step 2: Gather Materials
You’ll need a bucket, pliers or a wrench, a flashlight, rubber gloves, and a bottle brush or old toothbrush for this step.
Step 3: Locate the P-Trap
Get under your sink and locate the P-trap. It’s the u-shaped bend in the drainpipe that connects to the wall. You should be able to see the slip joint nuts on each side of the “j” bend of the trap.
Step 4: Remove Slip Joint Nuts
Using pliers or a wrench, loosen and remove the slip joint nuts on each side of the “j” bend of the trap. If they’re too tight, use a lubricant like WD-40 to help loosen them up. Be careful not to twist any supporting pipes.
Step 5: Remove P-Trap
Once you’ve removed the slip joint nuts, carefully remove the P-trap from the sink tailpiece and wall fitting. Hold onto it tightly as water may start to fall from the pipe depending on how full the trap is. Dump its contents into the bucket.
Step 6: Clean Out Debris
Inspect the P-trap for any lost items and remove any debris that may be clogging your drain. Use rubber gloves for this part if desired. Use a bottle brush or old toothbrush to scrub away any stubborn gunk stuck to the inside of the trap.
Step 7: Check for Corrosion or Leakage
Check for any corrosion or leakage in the slip joint nuts or gaskets that seal them. Replace any cracked gaskets and corroded nuts or pipes as needed.
Step 8: Reattach P-Trap
Reattach the P-trap by tightening the slip joint nuts on each side of the “j” bend of the trap with your hands and then with pliers or a wrench. Make sure everything is tight and secure before turning on water flow.
By following these steps, you can easily remove an old P-trap and clean out your pipes to prepare for installing a new one under your vanity sink.
Measure And Cut New P-Trap Assembly
When installing a new P-trap assembly, it’s important to measure and cut the pipes to the correct length before gluing them together. Here are the steps to follow:
Step 1: Wrap plumbing tape around the threaded outlet of the bathtub drain and screw on a 1 1/2-inch PVC female threaded adapter. Tighten it with adjustable pliers.
Step 2: Cut a 4-inch nipple from PVC pipe with a hacksaw, deburr the edges with a file and fit it inside. Make sure to measure the length of the nipple to fit between the trap adapter and the wall bend.
Step 3: Cut another piece of PVC pipe to connect the wall bend to the P-trap adapter. Measure the length needed for this piece of pipe and cut it with a hacksaw.
Step 4: Assemble the P-trap by connecting the nipple, wall bend, and P-trap adapter together. Do not glue any pipes until you have completed the trap assembly.
Step 5: Once you have assembled the P-trap, hold it up to the sink drain and make sure it fits properly. Adjust as needed before gluing any pipes together.
By following these steps, you can measure and cut a new P-trap assembly that fits perfectly under your vanity sink. Remember to double-check all measurements before gluing any pipes together to ensure a secure and leak-free installation.
Install New P-Trap Assembly
If you are installing a brand new sink, you will need to install a P-trap assembly to ensure proper drainage. Here are the steps to install a new P-trap assembly:
Step 1: Gather Your Materials
Before you begin, make sure you have all the necessary materials on hand. You’ll need a trap adapter, a wall bend (long elbow joint), a P-trap adapter (if not included in your kit), and a pop-up drain assembly for your sink.
Step 2: Mark and Cut the Hole
Use a laser level to mark the hole placement and ensure it is square with the vanity. Use a hole saw slightly larger than the diameter of your sink’s drain hole and slowly drill through the vanity top.
Step 3: Install the Trap Adapter
Attach the trap adapter to your sink’s drain pipe before proceeding. The trap adapter will allow you to use screw-on fittings in your setup. Attach the wall bend (long elbow joint) to your trap adapter.
Step 4: Install the P-Trap
If your kit does not come with a P-trap adapter, purchase one separately. Parts used for the connection include a P-trap kit that includes the marvel to PVC adapter, a 90 Degree 1-1/2in PVC Connector, and a short length of 1 1/2in PVC pipe. You’ll also need PVC cement glue and a hacksaw to cut the P-trap kit and PVC pipes to length.
Step 5: Connect to Wall Drain
Use a 90 Degree 1-1/2in PVC Connector Spigot x Socket for the lower connection to the wall drain if you have copper drain pipe. You do not need this if you have a PVC wall drain pipe.
Step 6: Final Install
Once all parts are connected, use PVC cement glue to secure them in place. Make sure everything is tight and secure before turning on water flow.